| Paper description |
In this paper, dynamic effective parameters of mass-type and stiffness-type perforated
thin-plate acoustic metamaterials (PAMs) are investigated by numerical simulations and
experiments to fundamentally reveal formation mechanisms of acoustic characteristics. The
perforated mass thin-plate acoustic metamaterial (PMAM) is proposed as a mass-type PAM,
the effective mass densities (EMDs) of unperforated mass thin-plate acoustic metamaterial
(UMAM) and PMAM are calculated by direct method and retrieval method, and formation
mechanisms of unusual values are analyzed by EMD defnition and simulated felds. A new
anti-resonance frequency is produced by perforation, at where EMD is much higher than
the static bulk-averaged values. In particular, EMD of PMAM is equal to that of UMAM
in parallel with the air hole when perforation radius is small, but the relationship is broken
when perforation radius is big. The perforated frame thin-plate acoustic metamaterial (PFAM)
is proposed as a stiffness-type PAM, the EMDs calculated in numerical simulations and
experiments verify the perforation effects revealed in mass-type PAM. In addition, the impacts
of perforation parameters on EMD show variation trends of resonance and anti-resonance
frequencies are different in two types of PAMs because perforations change system mass in
the PMAM but change stiffness in the PFAM. Thus this work is of guiding signifcance to
understand the acoustic characteristics of PAM from the perspective of dynamic effective
parameters. |
(创新港)
